Conventionally, a refrigerating apparatus is known which includes a refrigerant circuit that performs vapor compression refrigeration cycle by circulating a refrigerant. This refrigerating apparatus is composed of indoor and outdoor units connected with each other through communication pipes. The communication pipes are buried inside a building in many cases. This causes difficulty in exchanging the communication pipes at renewal of the refrigerating apparatus, necessitating introduction of a new refrigerating apparatus using the existing communication pipes.
Meanwhile, a CFC refrigerant and an HCFC refrigerant, which had been employed as a refrigerant filled in a refrigerant circuit until now, have been abolished because they causes adverse influence over environment (destruction of the ozone layer and the like). For this reason, it is required to connect a refrigerating apparatus using an HFC refrigerant or the like, which is a novel refrigerant, to the existing communication pipes that have used the CFC refrigerant or the HCFC refrigerant. However, the existing communication pipes include residual mineral oil of refrigerating machine oil for the CFC refrigerant or the HCFC refrigerant. Acids and ions generated due to degradation of the CFC refrigerant, the HCFC refrigerant, and the mineral oil may invite corrosion of an expansion valve and the like. Therefore, it is necessary to remove the mineral oil by cleaning the existing communication pipes before test run for a newly introduced refrigerating apparatus.
In this connection, a refrigerating apparatus capable of cleaning such existing communication pipes has been proposed (for example, see Patent Document 1). In this refrigerating apparatus, a refrigerant circuit is composed in such a fashion that a heat source unit including a compressor and a heat source side heat exchanger is connected to an indoor unit including a user side heat exchanger through first and second connection pipes as the existing communication pipes. On the suction side of the compressor, foreign matter catching means is provided for separating and recovering mineral oil and foreign matters from a refrigerant. The refrigerating apparatus performs cleaning operation in a cooling operation mode after an HFC refrigerant is filled to clean the first and second connection pipes by the refrigerant circulating in the refrigerant circuit, thereby recovering the mineral oil and the foreign matters.
Patent Document 1: Japanese Patent Application Laid Open Publication No. 2000-329432A